Switched-Gain Guidance for Impact Angle Control Under Physical Constraints

The nonlinear impact angle control problem of a physically constrained pursuer against a stationary ground target is solved through the use of a two-phased proportional navigation guidance scheme. The look angle and acceleration constraints are handled by numerically solving for the required values of the midcourse and terminal navigation gains. Different formulations are presented for three cases. The first one is the unrealistic case of constant velocity included for demonstration purposes. The second one is the more realistic case of constant maximum lift coefficient that is likely to suit subsonic ground-to-ground engagements. The last one is the adaptive update case that is intended for pursuers experiencing wide flight regimes. A simple range observer is also introduced to supplement the last case. The performance of the proposed technique is illustrated with simulations.